According to an example, aggregation based event identification may include aggregating each of a plurality of source events by an event type of event types that represent dusters of the source events and/or a host of a source event of the source events to generate a reduced number of the source events. Aggregation based event identification may further include analyzing a characteristic for each of the reduced number of the source events, and assigning, based on the analysis of the characteristic for each of the reduced number of the source events, a characteristic weight to each of the reduced number of the source events. Further, aggregation based event identification may include aggregating the characteristic weights for each of the reduced number of the source events to determine an aggregated event issue weight for each of the reduced number of the source events.